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Published on: 02/10/2026 - 14:36

Taste may seem like a simple sense: sweet, salty, bitter or sour. But behind these feelings is a precise system of cells, receptors and nerve signals. With the discovery of umami, and then accumulating evidence of the mouth's ability to detect certain fatty acids, scientists' questions about the number of basic tastes expanded. Is “Oligustos” the sixth flavour? Why did we develop this ability in the first place? These are all questions that will be present at the “Festival of Science,” which has been organized in France for 35 years and which this year chose the slogan “scientific tastes.”

Taste, or the sense of taste, is a sense that we know innately since childhood, since we taste the first foods. But once we dig a little deeper into this sense, we discover how difficult it is to describe it accurately. The combination of foods may give us complex feelings, ranging from pleasure to aversion. For decades, scientific studies have gradually revealed more secrets of the sense of taste. It has been shown that taste is not limited to salty, sweet, bitter and sour, and that there are other tastes that are being researched and studied. Research has also revealed that the sense of taste is linked to the evolution of humans and animals and their adaptation to their nutritional needs.

This occasion coincides with the selection of the sense of taste and its secrets as a main topic for the “Fête de la Science” in France. This event has been organized annually since 1991 to bring science and researchers closer to the general public, simplify scientific knowledge, and encourage critical thinking, especially among young people. In 2026, the 35th edition will be held under the slogan “Saveurs savantes”, to bring the public closer to the relationship between science, food, cooking and the sense of taste, through thousands of events across France, from October 2 to 12.

What is interesting about the matter is that the debate is still ongoing among specialists about the number of basic tastes that the sense of taste can perceive. This reveals an aspect of the complexity surrounding this sense and its mechanisms in the tongue, which is the main organ in the process of tasting.

The tongue, as is known, has small, prominent structures on its surface called lingual papillae. Part of these papillae contributes to the process of taste, as they contain inside or on their sides microscopic structures called “taste buds.” These buds consist of groups of cells specialized in receiving chemical signals and transmitting them via sensory nerves to the brain. Taste cells carry specialized proteins that can recognize specific molecules found in food, before converting this information into nerve signals. Detection mechanisms vary depending on the taste being detected.

Umami taste

Although it is easy for us to distinguish the tastes of sweet, sour, salty and bitter, many of us may not know the taste of umami. Umami is a fifth taste that has become scientifically recognized, in addition to the four traditional tastes. The Japanese word refers to a delicious and palatable taste that is difficult to describe in a few words. We find it in many foods, such as meat, ripe tomatoes, and soy sauce, and it is particularly linked to the presence of glutamate and some other compounds. Chefs have known this sensation for a long time, but the Japanese scientist Kikunae Ikeda was the first to study and describe it scientifically at the beginning of the twentieth century, after he isolated glutamate from Japanese seaweed broth, and called the sensation “umami.”

Subsequent studies showed the presence of receptors involved in umami detection in taste cells in humans and a number of animals, the most prominent of which is the T1R1/T1R3 complex receptor. With the accumulation of psychological, physiological and chemical evidence, umami has gradually become established, especially since the 1980s, as a fifth basic taste. The first international conference dedicated to umami, held in Hawaii in 1985, was an important stop on this path.

Towards a sixth basic taste?

For nearly two decades, there has been scientific debate about the possibility of adding another basic taste: the taste associated with fat. Our sense of fat does not result from taste alone. It also involves the sense of smell and the feeling of the texture and texture of food in the mouth. But several studies have shown that the mouth can also chemically detect some free fatty acids. Researchers have detected proteins involved in this process in human taste cells, including CD36 and GPR120. Accumulating evidence suggests that there is a real gustatory component to fatty acids, not just a sense of the texture or smell of fat.

In 2015, researchers proposed naming this sensation Oleogustus, after testing participants' ability to distinguish between different types of fatty acids. The study found that some fatty acids, especially medium- and long-chain fatty acids, produced a sensation that was distinguishable from other basic tastes.

But that does not mean that the "sixth taste" has become a settled reality. Researchers are still debating whether this sensation should be classified as a sixth basic taste, and what the precise mechanisms are behind it. Research indicates the involvement of more than one protein and mechanism, and the precise role of some of these receptors, including GPR120, is still a subject of research.

Scientists are also investigating whether a person's ability to detect fatty acids affects his food preferences and consumption of high-fat foods, and whether this has a role in some nutritional disorders such as obesity. But the relationship between these mechanisms and obesity is complex, and cannot be reduced to a single factor.

The role of taste in evolution

As is the case with sight, touch, and hearing, the sense of taste has been closely linked to the evolution of living organisms and their adaptation to their environments. It helps the organism distinguish between different food substances, and contributes to avoiding some substances that may be harmful. For example, a bitter taste can be a warning sign of some harmful or toxic compounds. In return, taste helps direct the organism towards food sources it needs. When we eat energy-rich foods, reward and motivation systems can be activated in the brain, including the dopamine system. Sugars are among the nutrients that can activate these systems, in addition to effects related to the nutritional value and energy provided by the food.

Sugars and carbohydrates provide an important and relatively quick source of energy, which made the ability to discover foods rich in them of evolutionary importance. But food sources rich in sugars were not always available in the same abundance in natural environments, so many animals had to search for them and take advantage of them when they became available, such as ripe fruits.

As for humans, their food environment has changed dramatically with the development of agriculture, industry, and technology. Today, we can obtain foods rich in energy and sugars easily and throughout the year. However, many of the basic biological mechanisms that influence our food preferences still exist. In a food environment where energy-dense foods are constantly available, some of these ancient preferences may conflict with our modern nutritional reality, which scientists are studying in the context of obesity and metabolic disorders.

This is only one facet of the complex relationship between humans and the sense of taste, a relationship that reveals, as we delve deeper into it, the intersection of biology, nutrition, behavior, and culture. It is among the aspects that this year's edition of Science Day in France opens to the public under the slogan "Educated Tastes."

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